Quadrene: A novel quasi-2D carbon allotrope with high carrier mobility

We present a comprehensive first-principles investigation of a novel carbon allotrope characterized by quasi-tetragonal atomic motifs and quasi-two-dimensional structural behavior. Structural analysis reveals an open framework composed of alternating diamond-like and square units, while thermodynamic assessments indicate a negative formation energy, suggesting high intrinsic stability. Phonon spectra confirm dynamical robustness, and ab initio molecular dynamics simulations at 1000 K validate its thermal resilience. Furthermore, the system exhibits an indirect bandgap of 1.58 eV at the HSE06 level, anisotropic mechanical behavior, and a broadband optical response, reinforcing its potential for nanoelectronic and optoelectronic applications. The highly anisotropic mechanical behavior is characterized by an in-plane Young’s modulus ranging from 80 to 550 GPa depending on crystallographic direction. Additionally, the electronic transport properties exhibit pronounced anisotropy, with hole mobilities reaching up to 2 . 1 × 1 0 6 cm 2 /V s and electron mobilities up to 6 . 40 × 1 0 6 cm 2 /V s along different crystallographic directions, highlighting the material’s promise for directionally selective nanoelectronic device applications.